Components of a gas turbine engine such as turbine nozzle segments are repaired and recoated by being washed with an alkaline washing solution, and then washed with an acid washing solution. Patent document 1 discloses a method for washing turbine nozzle segments with an alkaline solution containing sodium hydroxide and sodium permanganate, and then washing the washed turbine nozzle segments with a nitric acid aqueous solution of from 60% by volume to 80% by volume, to remove oxide from the turbine nozzle segments after being operated.
[Patent document 1] Japanese Patent Application Laid-open No. 2007-186786 (paragraphs 0010 and 0011)